Light-shielding film and method for producing light-shielding film

Abstract

For the light-shielding film, the glossiness of at least one surface when the incident angle is 60 degrees is set to a value in the range of 0 to 10, the optical density is set to a value in the range of 4 to 4, and the total thickness is set to a value in the range of 6 μm to 26 μm.

Description

Technical Field

[0001] The present invention relates to a light-shielding film and a method for producing the light-shielding film, and more specifically, to a light-shielding film used in optical applications, optical device applications, display device applications, mechanical parts, or electrical and electronic parts, and a method for producing the light-shielding film. Background Art

[0002] Light-shielding films are used in camera modules, which are optical components of electronic devices such as digital cameras and mobile phones, to suppress the generation and expansion of optical noise in lens units. In addition, light-shielding films are also used as gap adjustment components arranged between optical elements such as shutters, aperture components, or lenses in camera modules.

[0003] As the light-shielding film, for example, a black film colored black by adding carbon black to polyethylene terephthalate (PET) and having unevenness formed on the surface to impart light-shielding properties can be used. Figure 5 and 6 The light-shielding films 20 and 21 shown have a structure in which a light-shielding layer 202 is overlapped and arranged on at least one surface of a film substrate 201. The light-shielding layer 202 is formed of a resin that is a curable resin or a thermosetting resin, and black fine particles.

[0004] Such light-shielding films 20 and 21 are Figure 7 The light shielding films F7 and F8 are used in the conventional lens unit 30 shown in the figure. The lens unit 30 shown in the figure includes a sensor lens 33 housed in a tube 32, an infrared blocking filter 31, and a plurality of lenses L7 and L8. Figure 5 , 6 The light-shielding films 20 and 21 are respectively Figure 7 The lens unit 30 is provided with light-shielding films F7 and F8 corresponding to the lenses L7 and L8. In the lens unit 30, light-shielding films F7 and F8, one or more lenses L7 and L8, and a CMOS sensor are sequentially arranged along the traveling direction of the incident light. By providing light-shielding films F7 and F8 corresponding to the lenses L7 and L8, respectively, unnecessary light can be fully shielded.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application No. 2010-534342 Summary of the invention

[0008] Problems to be solved by the invention

[0009] In recent years, camera modules have been required to be smaller, thinner, and lighter in weight, depending on the devices they are mounted on. In addition, camera modules are required to have higher functionality, such as a wider range of zoom functions and a high-definition shooting function based on fine pixels. Such higher functionality is difficult to achieve in digital processing, for example, it is necessary to improve the optical zoom function of the lens unit of the camera module.

[0010] However, in order to make the lens unit highly functional, it is necessary to increase the number of lens pieces, for example. When a light-shielding film is configured corresponding to each lens, the total thickness of the light-shielding film also increases due to the increase in the number of lens pieces. As a result, the optical axis direction of the lens unit increases, making it difficult to miniaturize the lens unit. In the case where the device equipped with the camera module is a smartphone, for example, the lens unit may protrude from the housing, causing problems in the design of the device. This problem becomes significant as the number of light-shielding films increases.

[0011] As a countermeasure to this problem, for example, reducing the thickness of the light-shielding film is considered. However, if only the thickness of the light-shielding film is reduced, the light-shielding property of the light-shielding film will be reduced. Thus, in order to simultaneously achieve miniaturization and high functionality of the camera module, it is necessary to adjust the thickness while maintaining the performance of the light-shielding film.

[0012] Therefore, an object of the present invention is to reduce the thickness of a light-shielding film while maintaining good light-shielding properties.

[0013] Means for solving problems

[0014] In order to solve the above-mentioned problems, with respect to a light-shielding film involved in one embodiment of the present invention, the glossiness of at least one surface when the incident angle is 60 degrees is set to a value in the range of 0 to 10, the optical density at a wavelength in the range of 380 nm to 780 nm is set to a value in the range of 4 to 4, and the total thickness is set to a value in the range of 6 μm to 26 μm.

[0015] According to the above configuration, the glossiness of at least one surface of the light-shielding film is set to a value in the range of 0 to 10, so that the surface can be given a high light scattering property (anti-reflection property) that scatters incident light well. In addition, the optical density of the light-shielding film is set to a value in the range of 4 or more, and the total thickness is set to a value in the range of 6 μm to 26 μm, so even if the thickness of the light-shielding film is reduced, good light-shielding properties can be maintained.

[0016] The invention comprises a film substrate having light-shielding properties and a scattering layer which is arranged to overlap with the film substrate and scatter incident light, and the one surface may be a surface of the scattering layer on the opposite side to the film substrate.

[0017] Thus, even if the thickness of the scattering layer is reduced, the light-shielding effect of the light-shielding film can be well maintained by the light-shielding film substrate. Therefore, the total thickness of the light-shielding film can be easily reduced. In addition, good light scattering properties can be obtained on the surface of the scattering layer that is opposite to the light-shielding film substrate. In addition, by using a scattering layer that is separate from the light-shielding film substrate, the degree of freedom in designing the scattering layer can be increased.

[0018] The content of the black component in the scattering layer can be set to a value greater than 0 wt % and less than 4 wt %. In the light-shielding film, the film substrate has light-shielding properties, so the content of the black component in the scattering layer can be a trace amount. Even with such a configuration, the light-shielding properties of the light-shielding film can be ensured.

[0019] In addition, in the above-mentioned structure, the amount of black components in the scattering layer is suppressed. Therefore, for example, when a resin material having ultraviolet curing properties is used to form the scattering layer, ultraviolet rays can be irradiated to cure the resin material and form a good scattering layer. According to this method, compared with a method of using a thermosetting resin material to form the scattering layer, heat is not easy to reach the film substrate having light-shielding properties. Therefore, the possibility of heat shrinkage of the film substrate having light-shielding properties is small, so the thickness of the film substrate having light-shielding properties can be reduced. As a result, the total thickness of the light-shielding film can be reduced.

[0020] The scattering layer may further include: a resin member arranged along the surface of the film substrate; and particles dispersed inside the resin member. According to this configuration, the particles can be used to impart a concave-convex shape to the surface of the scattering layer. In addition, the light scattering property inside the scattering layer can be improved. Thus, the scattering layer can be imparted with good light scattering property.

[0021] The thickness of the film substrate may be set to a value in the range of 2 μm to 12 μm. According to such a configuration, by using a light-shielding film substrate, the thickness of the light-shielding film substrate can be reduced while maintaining the light-shielding property of the light-shielding film.

[0022] The thickness of the scattering layer can be set to a value in the range of 3 μm to 7 μm. In the light-shielding film, the film substrate has light-shielding properties, and the scattering layer may not have light-shielding properties, so the thickness of the scattering layer can be reduced. Therefore, the total thickness of the light-shielding film can be reduced.

[0023] The total light transmittance of the scattering layer may be set to a value in the range of 70% to 100%. By configuring the scattering layer in this way, the blackness of the light-shielding film can be well obtained by using the light-shielding film substrate.

[0024] The refractive index of the resin member may be set to a value in the range of 1.3 to 1.9. By configuring the scattering layer in this way, incident light entering the scattering layer can be easily scattered.

[0025] A method for producing a light-shielding film according to one embodiment of the present invention includes the following steps:

[0026] A preparation step of preparing a coating liquid containing a resin material having ultraviolet curability and electron beam curability and a film substrate having light-shielding properties;

[0027] In the first step, the coating liquid is applied to the surface of the film substrate and dried to form a coating film on the surface, and the coating film is irradiated with ultraviolet rays; and,

[0028] In a second step, the coating film irradiated with the ultraviolet rays is irradiated with an electron beam.

[0029] By performing the first step and the second step, a scattering layer is formed from the coating film, wherein the glossiness of the scattering layer at a surface opposite to the film substrate at an incident angle of 60 degrees is set to a value in the range of 0 to 10.

[0030] A light-shielding film is formed, the light-shielding film comprising the film substrate and the scattering layer, the optical density at a wavelength of 380 nm to 780 nm being set to a value in the range of 4 or more, and the total thickness being set to a value in the range of 6 μm to 26 μm.

[0031] According to the above manufacturing method, high light scattering properties can be exhibited by setting the glossiness to a value in the range of 0 to 10, and a light-shielding film can be manufactured in which the optical density is set to a value in the range of 4 or more and the total thickness is set to a value in the range of 6 μm to 26 μm. Therefore, a light-shielding film that can maintain good light-shielding properties despite a small total thickness can be obtained.

[0032] In addition, by performing the second step in addition to the first step, even if the coating film contains a certain degree of black component, the coating film can be well cured. In addition, there is no need for a heat treatment to cure the scattering layer. Therefore, in the manufacture of the light-shielding film, the film substrate with light-shielding properties will not shrink thermally. Therefore, even if the thickness of the film substrate with light-shielding properties is reduced to a certain extent, the shrinkage of the film substrate can be prevented. Thus, the total thickness of the light-shielding film can be reduced.

[0033] In the second step, the coating film may be irradiated with an electron beam in a state where a transfer member having a transfer surface formed with concavo-convex shapes is arranged so that the transfer surface is attached to the surface of the coating film on the opposite side to the film substrate, thereby forming the scattering layer to which the concavo-convex shapes are transferred. Thus, the concavo-convex shapes formed on the transfer surface of the transfer member can be efficiently transferred to the surface of the scattering layer.

[0034] In the first step, the coating films are formed on both surfaces of the film substrate, and in the second step, the film substrate is irradiated with electron beams from one side of the film substrate so as to penetrate the film substrate, thereby irradiating the coating films with electron beams. In this way, scattering layers can be efficiently arranged on both surfaces of the film substrate having light-shielding properties at the same time.

[0035] In the preparation step, the coating solution may be prepared so that the content of the black component in the scattering layer is greater than 0 wt % and less than 4 wt %. Thus, the transmittance of the coating film to ultraviolet rays and electron beams can be maintained. Therefore, the scattering layer can be well formed using the resin material.

[0036] In the preparation step, the coating solution further comprising particles may be prepared. According to this method, the surface of the scattering layer can be formed into a concavo-convex shape by using particles. In addition, the light scattering property inside the scattering layer can be improved. Therefore, the light scattering property can be easily imparted to the scattering layer.

[0037] In the second step, the scattering layer may be formed by a resin member having a refractive index set to a value in a range of 1.3 to 1.9. Thus, a scattering layer that easily scatters incident light can be formed.

[0038] In the preparation step, the film substrate having a thickness set to a value in the range of 2 μm to 12 μm can be prepared. According to the manufacturing method, the thickness of the film substrate having light-shielding properties can be well reduced while maintaining the light-shielding properties of the light-shielding film. In addition, since the scattering layer is formed through the first step and the second step, heat is not easy to reach the film component. Therefore, even if such a thin film substrate having light-shielding properties is used, the following problems can be prevented from occurring: the film component shrinks due to the heating accompanying the formation of the scattering layer, and wrinkles, waving, curling, etc. are generated, making it difficult to perform processing such as stamping normally.

[0039] In the second step, the scattering layer may be formed from the coating film with a thickness set to a value in the range of 3 μm or more and 7 μm or less. In the light-shielding film, the film substrate has light-shielding properties, and the scattering layer may not have light-shielding properties, so the thickness of the scattering layer can be reduced. Therefore, the total thickness of the light-shielding film can be easily reduced.

[0040] In the second step, a scattering layer having a total light transmittance set to a value in the range of 70% to 100% can be formed from the coating film. By forming the scattering layer in this way, electron beams can be transmitted from the outside to the resin material in the coating solution, thereby facilitating efficient curing of the resin material.

[0041] Effects of the Invention

[0042] According to each aspect of the present invention, the thickness of the light-shielding film can be reduced while maintaining good light-shielding properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] [ Figure 1 ] is a disassembled view of the optical components involved in the first embodiment.

[0044] [ Figure 2 ] is a cross-sectional view of the light-shielding film involved in the first embodiment.

[0045] [ Figure 3 ] (a) is a diagram showing a coating film forming step. (b) is a diagram showing the first step. (c) is a cross-sectional view showing the second step.

[0046] [ Figure 4 ] is an enlarged cross-sectional view of the scattering layer of the light-shielding film involved in the second embodiment.

[0047] [ Figure 5 ] is a cross-sectional view of a conventional light-shielding film.

[0048] [ Figure 6 ] is a cross-sectional view of a conventional light-shielding film.

[0049] [ Figure 7 ] is a partial cross section of a conventional lens unit. DETAILED DESCRIPTION

[0050] Hereinafter, each embodiment will be described with reference to the drawings.

[0051] (First embodiment)

[0052] [Light-shielding film]

[0053] Figure 1 FIG. 1 is an exploded view of the optical component 10 according to the first embodiment. Figure 1 As shown, the optical component 10 includes a plurality of light-shielding films F1 to F6, a plurality of optical components (here, lenses L1 to L6), and a housing (lens barrel) 11 for accommodating the light-shielding films F1 to F6 and the optical components. As an example, the light-shielding film 1 is arranged between adjacent optical components in a manner of surrounding the optical axis R. The number of light-shielding films and the number of optical components included in the optical component 10 are not limited.

[0054] Next, a specific configuration example of the light-shielding film 1 will be described. Figure 2 1 is a cross-sectional view of the light-shielding film 1 according to the first embodiment. Figure 1 The same is true for the light-shielding films F1 to F6. Figure 2 As shown, the light-shielding film 1 of the present embodiment includes: a film substrate 2 having a light-shielding property; and at least one scattering layer 3 .

[0055] The film substrate 2 shields the incident light incident on the light-shielding film 1. The optical density (OD value) of the film substrate 2 is set to a value in the range of 4 or more. Here, the total light transmittance of the film substrate 2 is set to a value in the range of 1% or less. As for the film substrate 2, in order to have light-shielding properties, as an example, it is opaque, and here it is black. As an example, the film substrate 2 contains a black component and a resin. In the present embodiment, the black component is a black pigment, and the resin is PET. The film substrate 2 is formed by extrusion molding a PET resin containing a black pigment, and biaxially stretching it. It should be noted that the black component may also be a substance other than a pigment (such as a dye, a colorant). The film substrate 2 may also be colored in a color other than black.

[0056] As the material of the film substrate 2, various polymer materials can be cited, for example. As the material, thermosetting resins, thermoplastic resins, and photocurable resins can be cited, for example. Among them, as thermoplastic resins, for example, polyolefins, acrylic resins, polyesters, polycarbonates, and polyamides can be cited. These materials can be used alone or in combination of two or more. Among them, from the viewpoint of ensuring strength, for example, cyclic polyolefins, polyalkylene arylates (polyethylene terephthalate (PET), polyethylene naphthalate (PEN)), polymethyl methacrylate resins, bisphenol A type polycarbonate, cellulose esters, etc. are preferred. In addition, from the viewpoint of dimensional stability and rigidity, biaxially stretched film materials are preferred. As such a film material, a film (such as PET film, PEN film) formed by biaxially stretched polyalkylene arylate is further preferred. Among them, from the aspect of being able to make the thickness thin and easy to obtain, a PET film is preferred.

[0057] There is no particular limitation on the method for manufacturing the film substrate 2. For example, the following manufacturing method can be cited: a black component (for example, a pigment, a dye, or a colorant) and a resin component are melt-kneaded, and the obtained material is formed into a film and stretched. According to this manufacturing method, a film substrate 2 having light-shielding properties can be formed with a single structure without overlapping multiple materials, so it is preferred.

[0058] In addition, as a method for manufacturing the film substrate 2, there can be mentioned a method for forming a colored layer on one or both sides of a resin film (e.g., a biaxially stretched polyester film). In the case of the method for forming the colored layer, the colored layer can be formed by coating, transferring, or printing a colorant on a resin film. In this case, the colorant can be used in a state mixed with a resin material having fluidity, for example.

[0059] As the coating method of colorant, known methods such as gravure coating method, dip coating, reverse roll coating method, extrusion coating method can be exemplified. In addition, as the printing method of colorant, known methods such as inkjet method, silk screen method can be exemplified. As the colorant of coating, transfer or printing on resin film, from the viewpoints such as the ease of penetration to resin film, it is preferred to use such as sublimation pigment. In addition, it is also possible to use general pigments in fiber applications, resin applications and inkjet applications etc.

[0060] In addition, a method for dyeing the resin film by immersing the resin film in a solution containing a dye can be mentioned. As a method for dyeing the resin film, a known method can be used. In the present embodiment, the resin film thus dyed can also be used as a film substrate 2. The film formed by polyester, nylon, acetate, polycarbonate, acrylic acid compounds, etc. can be easily dyed by immersing it in a dye dispersed in water.

[0061] The thickness of the film substrate 2 can be appropriately set, and as an example, is set to a value in the range of 2 μm to 12 μm. With respect to the film substrate 2, by setting the optical density at a value in the range of 380 nm to 780 nm to a value in the range of 4 or more, the incident light is not easy to penetrate from the side to the inside.

[0062] The scattering layer 3 is arranged to overlap at least one surface (here, both surfaces) of the film substrate 2, and scatters the incident light. The scattering layer 3 has light transmittance. When the scattering layer 3 is arranged to overlap, for example, an optical component, it scatters the incident light incident on the optical component from the side. The scattering layer 3 of this embodiment includes: a resin component 4 arranged along the surface of the film substrate 2; and black particles 5 that are a black component dispersed inside the resin component 4.

[0063] The black component of the scattering layer 3 absorbs the incident light incident on the scattering layer 3. Here, the content of the black component of the scattering layer 3 is set to a value in the range of greater than 0 weight % and less than 4 weight %. That is, the content of the black component of the scattering layer 3 is set to a trace amount. Thus, the scattering layer 3 has transparency. The total light transmittance of the scattering layer 3 of this embodiment is set to a value in the range of greater than 70% and less than 100%. It should be noted that the scattering layer 3 may not contain the black component.

[0064] Here, the total light transmittance of the scattering layer 3 can be obtained from the difference between the total light transmittance of the light-shielding film 1 and the total light transmittance of the film substrate 2. In the case where the scattering layer 3 is formed on both sides of the film substrate 2, the difference between the total light transmittance of the light-shielding film 1 and the total light transmittance of the film substrate 2 is equivalent to the sum of the total light transmittances of the scattering layers 3 on both sides. The total light transmittance of the film substrate 2 is greater than the total light transmittance of the light-shielding film 1 and is sufficiently smaller than the total light transmittance of the scattering layer 3. As an example, the total light transmittance of the light-shielding film 1 is 0, and the total light transmittance of the film substrate 2 is equal to or slightly higher than the total light transmittance of the light-shielding film 1. In contrast, the total light transmittance of the scattering layer 3 is a value in the range of 70 to 100.

[0065] The thickness of the scattering layer 3 can be appropriately set, and as an example, is set to a value in the range of 3 μm or more and 7 μm or less. The thickness of the scattering layer 3 may be smaller than the thickness of the film substrate 2. In the light-shielding film 1, the light-shielding property is ensured by the film substrate 2, so the thickness of the scattering layer 3 can be reduced. In addition, the refractive index of the resin member 4 is set to a value in the range of 1.3 or more and 1.9 or less.

[0066] The refractive index of the resin member 4 is inherent to the material of the resin member 4, and can be confirmed by analyzing the resin member 4 using, for example, an analysis device such as NMR or IR. In other words, by measuring the scattering layer 3 using an analysis device such as NMR or IR, the resin member 4 of the scattering layer 3 can be identified. The refractive index of the resin member 4 may be any value from literature or a measured value. In addition, when the total light transmittance of the scattering layer 3 is sufficiently high, the Abbe number of the scattering layer 3 may be directly measured by using an Abbe refractometer or an ellipsometer (for example, "KOBRA-WPR" manufactured by Oji Scientific Instruments Co., Ltd.) in accordance with JIS K 7142:2008, and the measured value may be used as the refractive index of the resin member 4.

[0067] Here, in the light-shielding film 1, the glossiness of at least one surface (here, both surfaces) of the scattering layer 3 when the incident angle is 60 degrees is set to a value in the range of 0 to 10, the optical density at a wavelength in the range of 380 nm to 780 nm is set to a value in the range of 4 or more, and the total thickness is set to a value in the range of 6 μm to 26 μm.

[0068] In this way, the surface 3a of the scattering layer 3 is set so that the surface 3a has light scattering properties. As described later, as an example, the shape of the surface 3a of the scattering layer 3 is formed by transferring the concavo-convexity of the transfer surface 8a of the transfer member 8 when manufacturing the light-shielding film 1. It should be noted that the shape of the surface 3a of the scattering layer 3 can also be formed by other methods. In addition, an adhesive layer for improving the adhesion between the film substrate 2 and the scattering layer 3 can be provided on the surface of the film substrate 2 opposite to the scattering layer 3.

[0069] The resin member 4 includes a binder resin 6 and a polymerization initiator of a precursor of the binder resin 6. The precursor of the binder resin 6 has ultraviolet (UV) curing properties and electron beam (EB) curing properties. Examples of the binder resin 6 include photocurable resins.

[0070] Examples of the black component contained in the film substrate 2 and the scattering layer 3 include carbon black, lamp black, grape black, peach black, bone carbon, carbon nanotubes, silver oxide, zinc oxide, magnetite-type ferrosoferric oxide, composite oxides of copper and chromium, composite oxides of copper, chromium and zinc, and black glass.

[0071] The black particles 5 of this embodiment are spherical, and the primary particle size is set to a value in the range of 10 nm to 500 nm. In addition, as an example, the surface resistance value of the scattering layer 3 is set to 1×10 12 By setting in this way, the light-shielding film 1 can be suitably used as an insulating member.

[0072] In addition, the glossiness at 60 degrees can be measured by the measurement method in accordance with JIS Z 8741. Regarding the primary particle size, a photograph of the particle surface magnified 100,000 times by a field emission scanning electron microscope ("JSM-6700F" manufactured by JEOL Ltd.) can be taken, and the magnified photograph can be further enlarged as needed, and for 50 or more particles, a ruler, caliper, etc. can be used to measure the average particle size of the number.

[0073] In addition, regarding the optical density, a densitometer ("X-Rite341C" manufactured by Videojet X-Rite Co., Ltd.) can be used to irradiate the sample with a vertical transmission beam, and the ratio to the state without the sample is expressed in log form. The beam width at this time can be measured as a circle with a diameter of 2 mm.

[0074] As described above, in this embodiment, the glossiness of at least one surface of the light-shielding film 1 is set to a value in the range of 0 to 10, so that the surface can be given a high light scattering property (anti-reflection property) that scatters incident light well. In addition, the optical density of the light-shielding film 1 is set to a value in the range of 4 or more, and the total thickness is set to a value in the range of 6 μm to 26 μm, so even if the thickness of the light-shielding film 1 is reduced, good light-shielding properties can be maintained.

[0075] In addition, the total thickness of the plurality of light-shielding films 1 can be reduced, so even when the housing 11 accommodates a plurality of optical components (lenses L1 to L6) and a plurality of light-shielding films F1 to F6, the size of the housing 11 in the direction of the optical axis R can be reduced. As a result, the size of the optical component 10 having the housing 11 in the direction of the optical axis R can be reduced. Therefore, the optical component 10 can be easily thinned and miniaturized. In addition, by miniaturizing the housing 11, it is possible to suppress the area of ​​the surface of the optical component 10 that overlaps with the housing 11 from protruding outward compared to the surrounding area of ​​the area, and it is also possible to easily flatten the surface of the optical component 10.

[0076] The light-shielding film 1 of the present embodiment includes a film substrate 2 and a scattering layer 3 that is arranged to overlap with the film substrate 2 and scatter incident light. The one surface whose glossiness is set to the above value is a surface 3a of the scattering layer 3 that is opposite to the film substrate 2.

[0077] Thus, even if the thickness of the scattering layer 3 is reduced, for example, the light-shielding effect of the light-shielding film 1 can be maintained by the film substrate 2. Therefore, the total thickness of the light-shielding film 1 can be easily reduced. In addition, good light scattering properties can be obtained on the surface 3a of the scattering layer 3 that is opposite to the film substrate 2. In addition, by using a scattering layer 3 that is separate from the film substrate 2, the degree of freedom in designing the scattering layer 3 can be increased.

[0078] In addition, the scattering layer 3 of this embodiment has light transmittance. Therefore, when the scattering layer 3 is formed using a resin material having ultraviolet curing properties or electron beam curing properties, it is possible to suppress the shielding of ultraviolet rays and electron beams by components present in the resin material. Therefore, the scattering layer 3 can be well formed. In addition, as the material of the scattering layer 3, it is not necessary to use a resin material having thermosetting properties, so that, for example, even on a thin film, the scattering layer 3 can be obtained by irradiating ultraviolet rays or electron beams to the resin material.

[0079] In addition, the content of the black component in the scattering layer 3 of the present embodiment is set to a value in the range of greater than 0 wt % and less than 4 wt %. In the light-shielding film 1, since the film substrate 2 has light-shielding properties, the content of the black component in the scattering layer 3 can be a trace amount. Even with such a configuration, the light-shielding properties of the light-shielding film 1 can be ensured.

[0080] In addition, the thickness of the film substrate 2 is set to a value in the range of 2 μm or more and 12 μm or less. According to such a configuration, by using the film substrate 2, the thickness of the film substrate 2 can be reduced while maintaining the light-shielding property of the light-shielding film 1. In addition, in the light-shielding film 1, it is not necessary to form the scattering layer 3 by thermal curing, so even if the thickness of the film substrate 2 is reduced, the occurrence of problems caused by the thermal shrinkage of the film substrate 2 can be prevented.

[0081] In addition, the scattering layer 3 is not required to have light-shielding properties. Therefore, the thickness of the scattering layer 3 in the present embodiment is set to a value in the range of 3 μm or more and 7 μm or less. In the light-shielding film 1, the film substrate 2 has light-shielding properties, and the scattering layer 3 does not need to have light-shielding properties, so the thickness of the scattering layer 3 can be reduced. Therefore, the total thickness of the light-shielding film 1 can be reduced.

[0082] In addition, the total light transmittance of the scattering layer 3 is set to a value in the range of 70% to 100%. By configuring the scattering layer 3 in this way, the blackness of the light-shielding film 1 can be well obtained by means of the film substrate 2. Such a scattering layer 3 can be configured, for example, by ultraviolet curing or electron beam curing of a resin material. In addition, the refractive index of the scattering layer 3 is set to a value in the range of 1.3 to 1.9. As a result, incident light entering the scattering layer 3 can be easily scattered.

[0083] [Method for producing light-shielding film]

[0084] Next, a method for producing the light-shielding film 1 will be exemplified. Figure 3 for Figure 1 A manufacturing flow chart of the light-shielding film 1. Figure 3 (a) is a diagram showing the first step S2. Figure 3 (b) is a diagram showing the first step S2. Figure 3 (c) is a diagram showing the second step S3.

[0085] The method for producing the light-shielding film 1 of the present embodiment includes a preparation step S1, a first step S2, a second step S3, and a peeling step S4. The light-shielding film 1 is produced by sequentially performing steps S1 to S4. Hereinafter, steps S1 to S4 will be specifically described.

[0086] In the preparation step S1, the operator prepares a coating liquid that is a raw material of the scattering layer 3 and a film substrate 2. Specifically, the operator dissolves a resin material having ultraviolet curability and electron beam curability in a solvent. Then, as an example, the operator adds a black component (black particles 5 in this embodiment) to the solvent. Thus, a coating liquid is obtained.

[0087] Here, the operator prepares the coating solution in a manner that the solid content concentration is greater than 5% by weight and less than 50% by weight (here, as an example, 30% by weight). In the present embodiment, since the resin material having ultraviolet curability and electron beam curability must be cured, a polymerization initiator of the resin material is further added to the coating solution. It should be noted that, in the case of not using a resin material having ultraviolet curability, the polymerization initiator is of course not required.

[0088] In addition, the operator prepares the film substrate 2 having light-shielding properties manufactured by the above-mentioned manufacturing method. The operator sets the film substrate 2 in a predetermined coating machine. The preparation step S1 is completed as described above.

[0089] Next, the operator performs the first step S2 according to the following steps. The first step S2 is a step of applying the above-prepared coating liquid to the surface of the film substrate 2 and drying it to form a coating film 15 on the surface, and then irradiating ultraviolet rays to the coating film 15. As an example, the first step S2 includes a coating film forming step, a transfer step, and an ultraviolet irradiation step as sub-steps.

[0090] Specifically, the operator applies the coating liquid to at least one surface of the film substrate 2. In this embodiment, as an example, in order to form the coating film 15 on both surfaces of the film substrate 2, the coating liquid is applied to each surface of the film substrate 2. The coating liquid may be applied to each surface of the film substrate 2 sequentially.

[0091] Then, the operator dries the coating liquid applied to each surface of the film substrate 2 using wind (here, hot wind), thereby forming a coating film 15 ( Figure 3 (a)). The above-mentioned coating film forming step is completed. It should be noted that the coating film 15 of this embodiment has a smooth surface and is not completely cured at the time point immediately after being formed.

[0092] Next, the operator uses the transfer member 8 having a predetermined transfer surface 8a, and performs a transfer step of transferring the surface shape of the transfer surface 8a of the transfer member 8 to the surface of the coating film 15 according to the following steps. When the surface shape formed on the coating film 15 is regarded as a positive shape, the transfer surface 8a of the transfer member 8 has a negative shape corresponding to the positive shape. In this embodiment, as the transfer member 8, a film member having ultraviolet transmittance and electron beam transmittance is used.

[0093] The operator makes the transfer member 8 bond to the coating film 15 formed on at least one surface of the film substrate 2. Thus, a composite body (hereinafter referred to as an intermediate body 16) is formed in which the transfer member 8 and the coating films 15 of the film substrate 2 are bonded. In the intermediate body 16, the surface shape of the transfer surface 8a of the transfer member 8 acts as a negative type, and the positive surface shape is transferred to the coating film 15. The transfer step is completed as described above.

[0094] Next, the operator performs the first step S2 of irradiating the intermediate 16 with ultraviolet rays according to the following steps. Figure 3 (b)) Thus, in the state where the transfer member 8 is bonded, the surface of the coating film 15 in contact with the transfer surface 8a is cured to a certain extent.

[0095] The transfer surface 8a of the transfer member 8 having a negative shape is formed with fine concavoconvexities. By transferring the fine concavoconvexities, light scattering properties are imparted to the scattering layer 3. In this embodiment, a film member having ultraviolet light transmittance and electron beam transmittance is used as the transfer member 8, so that a part of the resin material in the coating film 15 is cured by ultraviolet light through the transfer member 8. The first step S2 is completed as above. After the first step S2, the intermediate body 16 obtained is wound into a roll.

[0096] Here, the transfer member 8 of the present embodiment is described. The transfer member 8 contains a plurality of resin components. The transfer surface 8a has a fine concavo-convex shape of an island shape formed by a phase separation structure. On the surface 3a of the scattering layer 3, the light scattering property imparted to the surface 3a of the scattering layer 3 is determined by the shape of the transfer surface 8a of the transfer member 8. It should be noted that the so-called phase separation structure refers to a structure formed by metastable phase decomposition (wet metastable phase decomposition) of the liquid phase of the self-prepared liquid (which is the raw material of the transfer member 8). For details of the phase separation structure, for example, refer to Japanese Patent Gazette No. 6190581.

[0097] It should be noted that, in the present embodiment, the coating film 15 is not completely cured for the intermediate 16 at the time point after the first step S2 and before the second step S3. The coating film 15 has an uncured portion biased on, for example, the film substrate 2 side. In order to obtain the light-shielding film 1, it is necessary to completely cure the coating film 15. It should be noted that, in another embodiment, sometimes the coating film 15 is completely cured only by the ultraviolet irradiation step of the first step S2. In this case, the following second step S3 can be omitted.

[0098] Next, the operator unwinds the wound intermediate body 16 again and performs the second step S3 of irradiating the coating film 15 irradiated with ultraviolet rays in the first step S2 with electron beams. Thus, the resin material in the coating film 15 is completely cured, and the surface shape of the scattering layer 3 is formed.

[0099] According to the second step S3, the adhesion strength between the film substrate 2 and the scattering layer 3 can be improved. Therefore, the second step S3 is suitable for manufacturing the light-shielding film 1 including the film substrate 2 and the scattering layer 3 as in the present embodiment. In the second step S3, the intermediate 16 may be irradiated with electron beams only from one side or from both sides.

[0100] It should be noted that, for example, when the adhesion strength between the film substrate 2 and the scattering layer 3 is sufficient, the irradiation intensity of the electron beam can be reduced or the second step S3 can be omitted. That is, the second step S3 can be appropriately set or omitted according to the adhesion strength between the components required in the light-shielding film 1.

[0101] In addition, electron beams may not be used in the second step S3. For example, when the second step S3 is performed in a state where the transfer member 8 is not arranged on the coating film 15, ultraviolet rays may be used in the second step S3. In a state where the transfer member 8 is arranged on the coating film 15, electron beams are preferably used in the second step S3.

[0102] In addition, the intermediate body 16 may not be wound between the first step S2 and the second step S3. For example, depending on the embodiment, the first step S2 and the second step S3 may be performed continuously without winding the intermediate body 16.

[0103] Next, the operator performs a peeling step S4 of peeling the transfer member 8 from the intermediate 16. When the transfer members 8 are arranged on both surfaces of the film substrate 2 as in the present embodiment, the transfer members 8 may be peeled off simultaneously, or may be peeled off sequentially from any one of them. As described above, by going through the peeling step S4, the light-shielding film 1 can be obtained.

[0104] According to the above-mentioned manufacturing method, by setting the glossiness of the surface at an incident angle of 60 degrees to a value in the range of 0 to 10, high light scattering properties can be exhibited, and the light-shielding film 1 having an optical density set to a value in the range of 4 or more and a total thickness set to a value in the range of 6 μm to 26 μm can be manufactured. Therefore, a light-shielding film 1 that can maintain high light-shielding properties even if the total thickness is thin can be obtained.

[0105] In addition, by performing the second step S3 in addition to the first step S2, even when the coating film 15 contains a certain amount of black components, the coating film 15 can be cured well. In addition, there is no need for a heating treatment for curing the scattering layer 3. Therefore, in the manufacture of the light-shielding film 1, the film substrate 2 does not shrink by heat. Therefore, even if the thickness of the film substrate 2 is reduced to a certain extent, the shrinkage of the film substrate 2 can be prevented. Thus, the total thickness of the light-shielding film 1 can be reduced.

[0106] In the second step S3 of the present embodiment, the transfer member 8 having the transfer surface 8a formed with the concavoconvex is arranged so that the transfer surface 8a is attached to the surface of the coating film 15 on the opposite side to the film substrate 2, and the coating film 15 is irradiated with an electron beam, thereby forming the scattering layer 3 to which the concavoconvex shape is transferred. Thus, the concavoconvex shape formed on the transfer surface 8a of the transfer member 8 can be efficiently transferred to the surface 3a of the scattering layer 3. In addition, even if the coating film 15 does not contain particles such as silica fine particles, light scattering properties can be imparted to the scattering layer 3.

[0107] In addition, in the first step S2 of the present embodiment, the coating films 15 are formed on both surfaces of the film substrate 2, and in the second step S3, the electron beam is irradiated from one side of the film substrate 2 so as to penetrate the film substrate 2, thereby irradiating each coating film 15 with an electron beam. Thus, the scattering layer 3 can be efficiently arranged on both surfaces of the film substrate 2 at the same time.

[0108] In the preparation step S1 of the present embodiment, a coating liquid is prepared in which the content of the black component of the scattering layer 3 is set to a range of more than 0 wt % and not more than 4 wt %. This can effectively prevent the permeability of the coating liquid to ultraviolet rays and electron beams from being reduced due to the black component, and the scattering layer 3 can be efficiently formed from the coating liquid.

[0109] In the preparation step S1, as an example, a film substrate 2 is prepared whose thickness is set to a value in the range of 2 μm or more and 12 μm or less. Thus, the thickness of the film substrate 2 can be reduced while maintaining the light-shielding property of the light-shielding film 1. In addition, since the scattering layer 3 is formed through the first step S2 and the second step S3, heat does not easily reach the film substrate 2. Therefore, even if such a thin film substrate 2 is used, the following problems can be prevented from occurring: the film substrate 2 shrinks due to heating accompanying the formation of the scattering layer 3, and wrinkles, waving, curling, etc. are generated, making it difficult to perform normal processing such as stamping.

[0110] In the second step S3, as an example, the scattering layer 3 having a thickness set to a value in the range of 3 μm or more and 7 μm or less is formed from the coating film 15. In the light-shielding film 1, the film substrate 2 has a light-shielding property, and the scattering layer 3 does not need to have a light-shielding property, so it is possible to reduce the thickness of the scattering layer 3. Therefore, the total thickness of the light-shielding film 1 can be easily reduced.

[0111] In the second step S3, as an example, a scattering layer 3 whose total light transmittance is set to a value in the range of 70% to 100% is formed from the coating film 15. By forming the scattering layer 3 in this way, electron beams are transmitted from the outside through the resin material in the coating liquid, thereby making it easy to efficiently cure the resin material.

[0112] In the second step S3, as an example, a scattering layer 3 is formed whose refractive index is set to a value in the range of 1.3 to 1.9. Thus, a scattering layer 3 that easily scatters incident light can be formed. Other embodiments will be described below, centering on the differences from the first embodiment.

[0113] (Second embodiment)

[0114] Figure 4 This is an enlarged cross-sectional view of a scattering layer 103 of a light-shielding film 101 according to the second embodiment. The scattering layer 103 is arranged to overlap at least one surface (here, both surfaces) of a film substrate 2, and scatters incident light. The scattering layer 103 includes: a resin member 4 arranged along the surface of the film substrate 2; and particles 7 dispersed inside the resin member 4.

[0115] The content of the black component of the scattering layer 103 is set to a value in the range of greater than 0 wt% and less than 4 wt%. Here, the scattering layer 103 of the present embodiment contains a black component (for example, black particles 5). The black component is dispersed inside the resin member 4. The particles 7 can be any of inorganic particles such as silica particles or organic particles such as acrylic particles. When the particles 7 are inorganic particles, for example, silica particles are preferred as the particles 7, and hollow silica particles are particularly preferred.

[0116] The scattering layer 103 has irregularities on its surface 103a due to the particles 7. Thus, the surface 103a of the scattering layer 103 has the same shape as the surface 3a of the scattering layer 3. It should be noted that the scattering layer 103 may not contain a black component as long as it contains the particles 7 to such an extent that irregularities can be formed on the surface 103a.

[0117] Thus, according to the scattering layer 103, the surface of the scattering layer 103 can be given a concavo-convex shape by the particles 7. Therefore, good light scattering properties can be given to the scattering layer 103. In addition, when the resin member 4 contains a black component in the above-mentioned weight range, by dispersing the black component in the resin member 4, the resin member 4 can be appropriately colored black.

[0118] When manufacturing the light-shielding film 101 of the second embodiment, a coating liquid similar to that of the first embodiment is prepared except that a predetermined amount of particles 7 is included. The coating liquid is used to form a coating film 15 on the surface of the film substrate 2, and then the coating film 15 is sequentially subjected to the first step S2 and the second step S3.

[0119] Here, in the second embodiment, the transfer step is not required in the first step S2. In the second embodiment, the surface of the coating film 15 becomes a concavo-convex shape immediately after the coating film forming step is completed. Therefore, the surface of the scattering layer 3 can be formed into a concavo-convex shape by using the particles 7 without going through the transfer step (without using the transfer member 8). Thus, the surface of the coating film 15 can be given light scattering properties.

[0120] In the second embodiment, the ultraviolet irradiation step and the second step S3 are sequentially performed to form the scattering layer 103. In the second embodiment, the transfer step may be performed to further provide the surface of the coating film 15 with irregularities by the transfer surface 8a of the transfer member 8.

[0121] The light-shielding film 101 has a total thickness, an optical density at a wavelength of 380 nm to 780 nm, a blackness (L ※ ), and the glossiness of the surface 103a of the scattering layer 103 are set in the same manner as the light-shielding film 1 of the first embodiment.

[0122] Here, L ※ Refers to CIE1976(L ※ , a ※ , b ※ ) One of the coordinate axes of the color space. ※ The value of L represents the brightness of the color, and is expressed in 100 levels from 0 to 100. Among the 100 levels, 0 is black and 100 is white. ※ The larger the value, the brighter the color.

[0123] As an example, the total thickness of the light-shielding film 101 is set to 16 μm, the optical density at a wavelength of 380 nm to 780 nm is set to 6.3, and the blackness (L ※ ) is set to 17.5, and the glossiness of the surface 103a of the scattering layer 103 at an incident angle of 60 degrees is set to 0.2.

[0124] In the light-shielding film 101 having the above-mentioned scattering layer 103, the same effect as that of the light-shielding film 1 is also exerted. In addition, the scattering layer 103 of the light-shielding film 101 has the resin member 4 and the particles 7. Therefore, the surface 103a of the scattering layer 103 can be given a concavo-convex shape by the particles 7. In addition, the light scattering property inside the scattering layer 103 can be improved. Thus, the light scattering property can be well given to the scattering layer 103. In addition, when the black particles 5 are dispersed in the resin member 4 within the above-mentioned weight range, the resin member 4 can be appropriately colored in black.

[0125] In addition, in the light-shielding film 101, the amount of black components of the scattering layer 103 is suppressed. Therefore, when the resin member 4 is composed of a resin material having ultraviolet curability and electron beam curability, for example, it is possible to suppress the ultraviolet rays and electron beams from being shielded by the black components. Therefore, the resin material can be cured well. Thus, even if the amount of the resin material used is small, the resin material can be cured, and the thickness of the scattering layer 103 can be easily reduced.

[0126] (Confirmation test)

[0127] Next, confirmation tests will be described, but the present invention is not limited to the following examples.

[0128] [Test 1]

[0129] According to the following procedure, light-shielding films 1 according to the first embodiment, namely Examples 1 and 2, and light-shielding film 101 according to the second embodiment, namely Example 3, were prepared as shown in Table 1. Comparative Examples 1 to 3 were prepared as comparative examples to Examples 1 to 3.

[0130] (Preparation of membrane substrate)

[0131] The film substrates 2 of Examples 1 to 3 were prepared by the following procedure. 95 wt% of polyethylene terephthalate and carbon black (CB-1) produced by a furnace method and having an average primary particle size of 18 nm were mixed.

[0132] 5 wt% were melt-kneaded in a vented extruder at 280°C to prepare a CB masterbatch. Separately, 98.0 wt% of polyethylene terephthalate and 2.0 wt% of silica particles having an average primary particle size of 2.6 μm were melt-kneaded in a vented extruder at 280°C to prepare a SiO masterbatch. 2 Masterbatch.

[0133] Next, 13 wt% of the CB masterbatch prepared in the above manner and SiO 2 1.5 wt% of the masterbatch and 85.5 wt% of PET were mixed to obtain a film material, which was extruded from a T-shaped nozzle into a sheet and wound on a mirror-surface cooling roll with a surface temperature of 20°C by an electrostatic casting method to obtain a film intermediate with a thickness of 55 μm.

[0134] The film intermediate obtained in the above manner was subjected to sequential biaxial stretching as follows using a biaxial stretching tester ("FILM STRETCHING TESTER" manufactured by Toyo Seiki Seisaku-sho). First, the film intermediate was heated to 90°C and stretched 2.8 times in its longitudinal (extrusion) direction. Next, the film intermediate was cooled, further heated to 130°C, and stretched 3.3 times in the transverse direction (film width direction). Then, the film intermediate was heat-treated at 180°C to obtain film substrates 2 of Examples 1 to 3 having a thickness of 6 μm.

[0135] In addition, the film substrates of Comparative Examples 1 to 3 were prepared as follows. SiO 2 A transparent PET film with a thickness of 6 μm was prepared in the same manner as in Examples 1 to 3 except that the masterbatch was set to 1.7 wt % and the PET was set to 98.3 wt % to obtain a film raw material, as the film substrates of Comparative Examples 1 and 3. In addition, as the film substrate of Comparative Example 2, a commercially available transparent PET film with a thickness of 12 μm, namely, "TOYOBO ESTER Film E5100#12" manufactured by Toyobo Co., Ltd., was used.

[0136] (Preparation of transfer parts)

[0137] As the transfer member 8 of Examples 1 and 2, transfer members A and B of the following specifications were prepared. As the transfer member A, a member having a thickness of 50 μm and having a transfer surface 8a of which the arithmetic mean height Sa of the surface roughness was set to 0.666 μm, the maximum height Sz of the surface roughness was set to 6.177 μm, the total haze was set to 77.44, and the glossiness at an incident angle of 60 degrees was set to 3.3 was prepared. This transfer member A was used for the manufacture of Example 1.

[0138] As the transfer component B, a component having a thickness of 50 μm and having the following transfer surface 8a, wherein the arithmetic mean height Sa of the surface roughness of the transfer surface 8a is set to 1.156 μm, the maximum height Sz of the surface roughness is set to 12.483 μm, the total haze is set to 91.85, and the glossiness at an incident angle of 60 degrees is set to 1.3 is prepared. This transfer component B is used for the manufacture of Example 2. Both transfer components A and B contain multiple resin components and are formed by a film component having a phase separation structure of multiple resin components.

[0139] (Preparation of Scattering Layer)

[0140] The coating liquid used in Examples 1 and 2 was prepared as follows. The coating liquid contained, in terms of solid content ratio, 15 wt% of a black pigment (a 9 wt% MEK dispersion of carbon black (black fine particles) having an average primary particle size of 150 nm, "MHI Black #273" manufactured by Mikoku Color Co., Ltd.), 77 wt% of a resin A ("HR370" manufactured by Yokohama Rubber Co., Ltd.), and 8 wt% of a resin B ("Ultraviolet UV1700B" manufactured by Nippon Synthetic Chemical Co., Ltd.) as a multifunctional methacrylate compound. The coating liquid contained carbon black as a black pigment at a solid content concentration of 1.08 wt%. By using the coating liquid, the solid content concentration of carbon black as a black pigment in the scattering layer 3 of Examples 1 and 2 was set to 4 wt% and the maximum thickness was set to 4.5 μm.

[0141] In addition, the coating liquid used in Example 3 was prepared as follows. The coating liquid contained 10 wt% of "MHI Black #273" manufactured by Mikoku Pigments Co., Ltd., 33 wt% of resin A, 4 wt% of resin B, and 53 wt% of particles "SYLYSIA 448" manufactured by Fuji Silysia Chemical Ltd. in terms of solid content ratio. By using this coating liquid, the solid content concentration of carbon black as a black pigment in the scattering layer 103 of Example 3 was set to 4 wt%, and each thickness was set to 3.0 μm.

[0142] In addition, the coating liquid used in Comparative Examples 1 and 2 was prepared as follows. The coating liquid was prepared, which contained 64% by weight of "MHI Black #273" manufactured by Mikoku Color Co., Ltd., 27% by weight of resin A, and 9% by weight of resin B in terms of solid content ratio. In addition, the coating liquid used in Comparative Example 3 was prepared as follows. The coating liquid was prepared, which contained 37% by weight of "MHI Black #273" manufactured by Mikoku Color Co., Ltd., 16% by weight of resin A, 5% by weight of resin B, and 42% by weight of filler particles "SYLYSIA448" manufactured by Fuji Silysia Chemical Ltd. in terms of solid content ratio. By using these coating liquids, the solid content concentration of carbon black as a black pigment in the scattering layers of Comparative Examples 1 to 3 was set to 20% by weight.

[0143] Next, regarding Examples 1 and 2, Step 1 S2 and Step 1 S3 were performed according to the following procedure. Using each coating solution, a coating film 15 was formed on one surface of the film substrate 2, and a transfer member 8 was arranged to overlap the coating film 15, and the coating film 15 was irradiated with a cumulative light amount of 100 mJ / cm 2 through the transfer member 8. 2Then, the coating film 15 is formed on the other side of the film substrate 2 in the same manner as above, and the coating film 15 is irradiated with ultraviolet rays through the transfer member 8 while the transfer member 8 is overlapped and arranged on the coating film 15. Then, the intermediate 16 is wound.

[0144] Next, the wound intermediate body 16 is unwound again, and in the second step S3, each coating film 15 is irradiated with an electron beam having a cumulative electron beam dose (absorbed radiation dose) of 250 kGy at one time. Then, in the peeling step S4, the transfer member 8 is peeled off from each coating film 15 to obtain the light-shielding film 1 of Examples 1 and 2. In addition, the light-shielding film 101 of Example 3 is obtained by using the same manufacturing method as the manufacturing method of Examples 1 and 2 except that the coating liquid of Example 3 is used and the transfer step in the first step is omitted.

[0145] In addition, using the film substrates (transparent film substrates) and coating solutions of Comparative Examples 1 to 3, light-shielding films of Comparative Examples 1 to 3 were prepared, each of which had a transparent film substrate and a scattering layer (containing 20% ​​by weight of black particles as shown in Table 2) disposed so as to overlap both surfaces of the transparent film substrate. The maximum thickness of each scattering layer of Comparative Examples 1 and 2 was set to 9.5 μm, and the maximum thickness of each scattering layer of Comparative Example 3 was set to 10.0 μm.

[0146] The scattering layers of the light-shielding films of Comparative Examples 1 to 3 correspond to the scattering layers 3 of Examples 1 to 3, but differ from the scattering layers 3 having a certain degree of light transmittance in that the content of black particles is high and the films have light-shielding properties. The scattering layers of Comparative Examples 1 and 2 have a surface shape formed by including filler particles. In addition, the surface shape of the scattering layer of Comparative Example 3 is formed by the transfer surface of the transfer member.

[0147] For each of the light-shielding films of Examples 1 to 3 and Comparative Examples 1 to 3, the total thickness of the light-shielding film, the total light transmittance of the film substrate, the thickness of the film substrate, the optical density (OD value), the blackness (L ※ ), and glossiness when the incident angle is 60 degrees.

[0148] The total light transmittance (%) of the film substrate was measured using a haze meter (NDH-5000W manufactured by Nippon Denshoku Co., Ltd.) in accordance with JIS K7136. The optical density (OD value) was measured using a transmission densitometer (Model 341C manufactured by Xrite Corporation) in accordance with JIS-K 7361.

[0149] The glossiness at an incident angle of 60 degrees was measured according to JIS K7105 using a gloss meter (KT-GL0030 manufactured by TQC Therminport Quality Control Co., Ltd.). ※) was measured using a UV spectrophotometer (U3900H manufactured by Hitachi, Ltd.).

[0150] In addition, the total haze of the transfer parts A and B was measured using a HAZEMETER (NDH5000W model manufactured by Nippon Denshoku Co., Ltd.). The arithmetic mean height Sa and the maximum height Sz of the surface roughness were measured using a scanning white interference microscope (for example, VertScan R3300G model manufactured by Ryoka Systems Inc.). The measurement results are shown in Tables 1 and 2.

[0151] [Table 1]

[0152]

[0153] [Table 2]

[0154]

[0155] As shown in Tables 1 and 2, Examples 1 to 3 all obtained better results than Comparative Examples 1 to 3. It was confirmed that Examples 1 to 3 had substantially the same optical density (OD value) and blackness as Comparative Examples 1 to 3, and had a smaller total thickness than Comparative Examples 1 to 3.

[0156] Here, in Comparative Examples 1 to 3, it is necessary to ensure light-shielding properties through the scattering layer, and a relatively large amount of black component is contained. On the other hand, in order to maintain the surface hardness of the scattering layer at a certain value or above, it is necessary to increase the content of the binder resin. Therefore, it is considered that the maximum thickness of the scattering layer increases, and the total thickness of the light-shielding film also increases.

[0157] In contrast, in Examples 1 to 3, by using the film substrate 2, there are no problems associated with the content of the black component and the binder resin, and the maximum thickness of the scattering layer 3 can be reduced. As a result, the total thickness of the light-shielding film 1 of Examples 1 to 3 can be reduced well. As a result, it is considered that in Examples 1 to 3, the total thickness of the light-shielding film 1 can be reduced while ensuring good light-shielding properties.

[0158] It was also confirmed that Examples 1 to 3 had lower glossiness (60 degrees) than Comparative Examples 1 to 3 (especially Comparative Example 1) and had excellent light scattering properties. It was also confirmed that Example 2 had significantly lower glossiness than Example 1.

[0159] One reason for such a result is that the glossiness (60 degrees) of the surface 3a can be sufficiently reduced by forming the shape of the surface 3a of the scattering layer 3 by the transfer surface 8a of the transfer member 8. The above results confirm the superiority of Examples 1 to 3 over Comparative Examples 1 to 3.

[0160] [Test 2]

[0161] Next, light-shielding films of Comparative Examples 4 to 9 shown in the following Tables 3 and 4 were prepared, and the measurement results thereof were compared with the measurement results of Examples 1 to 3. Comparative Examples 4 to 9 were prepared under the same conditions as Example 1 except for the differences shown below.

[0162] Comparative Example 4 was prepared, which had the same structure as Example 1 except that a transparent (i.e., non-light-shielding) film substrate was used. Comparative Example 5 was prepared, which had the same structure as Comparative Example 4 except that the content of the black component in the scattering layer was set to 20% by weight and the resin curing method of the scattering layer was ultraviolet curing only.

[0163] Furthermore, Comparative Example 6 was prepared as follows: the content of the black component in the scattering layer was set to 20% by weight, the total light transmittance was set to a value in the range of 70% to 100%, and when the light-shielding film was prepared, the cumulative electron beam dose of the electron beam irradiated to each coating film serving as the basis of the light-shielding layer was set to 250 kGy. The same configuration as Comparative Example 4 was used.

[0164] Comparative Example 7 was prepared as follows: the content of the black component in the scattering layer was set to 20% by weight, and the maximum thickness of each scattering layer was set to 10.0 μm, and the same configuration as Comparative Example 4 was prepared. Comparative Example 8 was prepared as follows: the maximum thickness of each scattering layer was set to 8.0 μm, a thermosetting resin was used as the material of the scattering layer, and the resin curing method of the scattering layer was thermal curing, and the same configuration as Comparative Example 4 was prepared. Comparative Example 9 was prepared as follows: the content of the black component in the scattering layer was set to 20% by weight, the maximum thickness of each scattering layer was set to 8.0 μm, a thermosetting resin was used as the material of the scattering layer, and the resin curing method of the scattering layer was thermal curing, and the film substrate was a commercially available transparent PET film, namely, "TOYOBO ESTER Film E5007" manufactured by Toyobo Co., Ltd., and the same configuration as Comparative Example 4 was prepared.

[0165] Here, the scattering layers of Comparative Examples 8 and 9 were prepared using the following varnish (coating liquid) containing a thermosetting resin. Specifically, 13.0 wt% of epoxy resin ("YDCN-703" manufactured by Tohto Kasei Co., Ltd.) as a thermosetting resin, 11.0 wt% of phenolic resin ("XLC-LL" manufactured by Mitsui Chemicals, Inc.), 34 wt% of "MHI Black #273" manufactured by Mikoku Pigments Co., Ltd., 0.025 wt% of 1-cyanoethyl-2-phenylimidazole ("2PZ-CN" manufactured by Shikoku Kasei Co., Ltd.) as a curing accelerator, and 38 wt% of "SYLYSIA 448" manufactured by Fuji Silysia Chemical Ltd. as particles were dissolved in 4 wt% of cyclohexanone as an organic solvent. Then, these were mixed using a bead mill to prepare a varnish having a non-volatile component set to 15%. For Comparative Examples 4 to 9, the same measurements as those of Comparative Examples 1 to 3 were performed. The results are shown in Tables 3 and 4.

[0166] [Table 3]

[0167]

[0168] [Table 4]

[0169]

[0170] As shown in Tables 1, 3, and 4, Comparative Examples 4 to 9 are significantly different from Examples 1 to 3 in that the film substrate has no light-shielding property. It is known that the light-shielding property of Comparative Example 4 is low compared to Examples 1 to 3, and it is difficult to obtain an appropriate optical density. In addition, it is known that the content of the black component in the scattering layer of Comparative Example 5 is slightly increased compared to Comparative Example 4, so that the light-shielding property is slightly improved, but it is still difficult to obtain an appropriate optical density. In addition, in the scattering layer of Comparative Example 5, the curing of the resin is insufficient, and poor transfer of the surface shape of the transfer component A is confirmed.

[0171] In Comparative Example 6, the resin of the scattering layer was not sufficiently cured by the electron beam, so that the formation of the scattering layer was poor. In addition, due to the poor formation, the transfer member A could not be peeled off from the scattering layer, so that the OD value and the blackness (L ※ The reason for the uncured resin and poor molding of the scattering layer is that the scattering layer contains a large amount of black components, so ultraviolet rays and electron beams cannot fully penetrate from the outside to the inside of the coating film.

[0172] In Comparative Example 7, in which the maximum thickness of the scattering layer is large, such uncured resin of the scattering layer is also confirmed. In Comparative Example 8, since the resin of the scattering layer is cured by thermal curing, the light-shielding film is thermally shrunk when the resin of the scattering layer is thermally cured, and wrinkles are generated. In Comparative Example 9, since the thickness of the film substrate is significantly greater than that of Comparative Example 8, the generation of wrinkles confirmed in Comparative Example 8 is not observed, but the total thickness of the light-shielding film is also greatly increased. Based on the above test results, the superiority of Examples 1 to 3 over Comparative Examples 4 to 9 is confirmed.

[0173] The present invention is not limited to the embodiments, and the configuration and method may be changed, added, or deleted within the scope of the present invention. The black component of the scattering layer may include at least one of a pigment and a dye.

[0174] In addition, the transfer surface 8a of the transfer member 8 may be formed into projections and depressions by sandblasting. In addition, when the heat shrinkage of the film substrate 2 does not become a big problem when manufacturing the light-shielding film 1, a thermosetting resin may be used as a precursor of the binder resin 6. In addition, the particles 7 may not be dispersed inside the resin member 4 of the first embodiment.

[0175] When the resin member 4 is made of a UV-curable and electron-beam-curable resin material, the content of the black component in the scattering layer 3, 103 may be set to a value greater than 4 wt % within a permissible range that does not significantly affect the curing of the resin material.

[0176] Industrial Applicability

[0177] Thus, the light-shielding film of the present invention has an excellent effect of being able to reduce the thickness while maintaining good light-shielding properties. Therefore, it is beneficial to apply the present invention widely to light-shielding films and methods for producing light-shielding films that can exert this effect.

[0178] Description of Reference Numerals

[0179] 1. 101 light-shielding film

[0180] 2. Membrane substrate

[0181] 3.103 Scattering layer

[0182] 3a, 103a Surface of the scattering layer

[0183] 4 Resin parts

[0184] 5 Black particles

[0185] 7 particles

[0186] 8 Transfer parts

[0187] 8a Transfer surface of transfer unit

Claims

1. A light-shielding film comprising a film substrate and a scattering layer for scattering incident light, The scattering layer includes a black component and a resin member, wherein the content of the black component is set to a value in a range of greater than 0 wt % and not more than 4 wt %. The film substrate has light-shielding properties and is arranged to overlap with the scattering layer. The black component is any component selected from carbon black, lamp black, grape black, peach black, bone carbon, carbon nanotubes, silver oxide, zinc oxide, magnetite-type ferroferric oxide, composite oxide of copper and chromium, composite oxide of copper, chromium and zinc, and black glass. The film substrate includes a thermosetting resin or a thermoplastic resin, and the total light transmittance of the film substrate is set to a value within a range of 1% or less. In the light-shielding film, The glossiness of at least one surface when the incident angle is 60 degrees is set to a value in the range of 0 to 10, The optical density at a wavelength of 380 nm or more and 780 nm or less is set to a value in the range of 4 or more. The total thickness is set to a value in the range of 6 μm or more and 26 μm or less. Blackness (L ※ ) is set to a value in the range of 17.5 or more and 24.0 or less, and the blackness (L ※ ) is the brightness specified in JIS Z 8518.

2. The light-shielding film according to claim 1, wherein The one surface is a surface of the scattering layer on the opposite side to the film substrate.

3. The light-shielding film according to claim 1, wherein The scattering layer includes the resin member disposed along the surface of the film substrate and particles dispersed inside the resin member.

4. The light-shielding film according to claim 1, wherein The refractive index of the resin member is set to a value in the range of 1.3 to 1.

9.

5. The light-shielding film according to claim 1, wherein The thickness of the film substrate is set to a value in the range of 2 μm or more and 12 μm or less.

6. The light-shielding film according to any one of claims 1 to 5, wherein The thickness of the scattering layer is set to a value in the range of 3 μm to 7 μm.

7. The light-shielding film according to any one of claims 1 to 5, wherein The total light transmittance of the scattering layer is set to a value in the range of 70% to 100%.

8. A method for producing a light-shielding film, comprising: A preparation step of preparing a coating liquid containing a black component and a resin member having ultraviolet curability and electron beam curability and set so that the content of the black component in the scattering layer is greater than 0 wt % and less than 4 wt %, and a film substrate having a light-shielding property; In a first step, the coating liquid is applied to the surface of the film substrate and dried to form a coating film on the surface, and the coating film is irradiated with ultraviolet rays; and In a second step, the coating film irradiated with the ultraviolet rays is irradiated with an electron beam. In the first step, the coating solution containing the black component and the resin member and the film substrate containing a thermosetting resin, a thermoplastic resin or a photocurable resin and having a total light transmittance set to a value within a range of 1% or less are prepared. The black component is any component selected from carbon black, lamp black, grape black, peach black, bone carbon, carbon nanotubes, silver oxide, zinc oxide, magnetite-type ferroferric oxide, composite oxide of copper and chromium, composite oxide of copper, chromium and zinc, and black glass. By the first step and the second step, Thus, a scattering layer is formed by the coating film, the content of the black component in the scattering layer is set to a value in the range of greater than 0 wt % and less than 4 wt %, and the glossiness of the scattering layer at an incident angle of 60 degrees on a surface opposite to the film substrate is set to a value in the range of greater than 0 and less than 10, The light-shielding film is formed, the light-shielding film comprising the film substrate and the scattering layer, the optical density at a wavelength of 380 nm to 780 nm being set to a value in the range of 4 or more, the total thickness being set to a value in the range of 6 μm to 26 μm, and the blackness (L ※ ) is set to a value in the range of 17.5 or more and 24.0 or less, and the blackness (L ※ ) is the brightness specified in JIS Z 8518.

9. The method for producing a light-shielding film according to claim 8, wherein: In the second step, a transfer member having a transfer surface formed with projections and recesses is arranged so that the transfer surface adheres to the surface of the coating film opposite to the film substrate, and the coating film is irradiated with an electron beam, thereby forming the scattering layer having the projections and recesses transferred thereto.

10. The method for producing a light-shielding film according to claim 8, wherein: In the first step, the coating film is formed on both surfaces of the film substrate. In the second step, the film substrate is irradiated with an electron beam from one surface side of the film substrate so as to pass through the film substrate, thereby irradiating each coating film with an electron beam.

11. The method for producing a light-shielding film according to any one of claims 8 to 10, wherein: In the preparing step, the coating solution further including particles is prepared.

12. The method for producing a light-shielding film according to any one of claims 8 to 10, wherein: In the second step, the scattering layer is formed including a resin member whose refractive index is set to a value in a range of 1.3 to 1.

9.

13. The method for producing a light-shielding film according to any one of claims 8 to 10, wherein: In the preparation step, the film substrate having a thickness set to a value in a range of 2 μm or more and 12 μm or less is prepared.

14. The method for producing a light-shielding film according to any one of claims 8 to 10, wherein: In the second step, the scattering layer is formed from the coating film and has a thickness set to a value in a range of 3 μm to 7 μm.

15. The method for producing a light-shielding film according to any one of claims 8 to 10, wherein: In the second step, the scattering layer having a total light transmittance set to a value in a range of 70% to 100% is formed from the coating film.

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